A spokesperson for Morningstar also said Thursday that the company had contacted the Journal to request corrections to "numerous points that mischaracterize our business."

Ptak is the head of global manager research for Morningstar, according to his company bio.

The Journal's story raised serious questions about the effectiveness of Morningstar's coveted rating system. The paper examined the performance of thousands of funds that the company reviewed over nearly 15 years and found that funds the company rated highly failed to deliver.

"We strongly disagree with the interpretations that they drew," Ptak said on CNBC's "Power Lunch" on Thursday afternoon.

Shares of 'MORN' fell 4.6 percent to a close of $82.75 Wednesday on the news, the biggest loss in two years. The stock came roaring back on Thursday, rising more than 5 percent.

Ptak argued that according to the Journal's own analysis, the "odds of success were much higher in high-rated funds than low-rated funds." He cited the chart above that shows a fund's star rating in the left column as well as the fund's future rating in the second row.

The Journal acknowledges this in their story, writing "most five-star funds perform somewhat better than lower-rated ones, yet on the average, five-star funds eventually turn into merely ordinary performers."

Only 12 percent of funds awarded a five-star rating from Morningstar earned the same rating for the five years that followed the rating, the Journal wrote.

In a statement, a spokesperson for parent company Dow Jones said they stood by the Journal's reporting.

"The Wall Street Journal spent nearly a year thoroughly reviewing millions of data points in an effort to assess Morningstar's widely accepted star ratings. Our journalistic standards were fully applied, including extensive conversations with Morningstar about our analysis," spokesperson Colleen Schwartz wrote in an email.

In his article, Ptak noted conversations Morningstar had with the Journal, saying Morningstar had urged the Journal to alter a metric it used in its analysis. He said the Journal "opted against our advice."

Morningstar said in a statement that the company had read the Journal's article and "strongly disagree with the conclusions it reached."

He wrote that Morningstar's "biggest and best defense is to say, using the WSJ's own data, that five star funds were less likely to fail than 1 star funds."

"However, this is intuitive; a 1-star fund gets that ranking because its performance sucked before the fact," he wrote. "Fund companies will shut those products down rather than use marketing dollars to support them. So of course they are more likely to die than a five star fund, which attained its ranking thanks to good historical performance."